Burberry boss Angela Ahrendts has dismissed the idea of quotas to boost the number of women in the boardroom as "dangerous", despite growing evidence of discrimination in the business world and the prospect of just two female chief executives in the FTSE 100 next year.

Asked if she was in favour of the imposition of quotas, Ahrendts said on Wednesday: "I'm not. I think it's dangerous … Whether it's countries or companies, it's about putting the best person in the job who can unite people and create value. A man could do this job just as well as I can."

The American, who took the helm at the British fashion brand six years ago, added that it was not an issue that she fretted about: "I don't spend a lot of time thinking about this, what with three kids, running the company and being flat out busy."

The recent resignations of Pearson boss Dame Marjorie Scardino and Cynthia Carroll, the chief executive of mining firm Anglo American, have reignited the debate about why there is a dearth of women at the top of Britain's biggest companies. Their departures will leave just Ahrendts and Imperial Tobacco's Alison Cooper fronting FTSE 100 companies in 2013.

Pointing to the growing number of female university graduates, Ahrendts suggested it was just a matter of time before the gender balance improved.

Announcing her decision to leave the media and publishing group Pearson after 15 years in charge, Scardino – who also rejected quotas – sounded a less optimistic note, saying: "I thought, in 1997, that by the time I left Pearson, things would be different in terms of the number of chief executives and board members who are women. It's not really too different and, for that, I'm sorry."

Royal Mail's chief executive, Moya Greene, has also waded into the debate and is one of the few top female bosses to support the introduction of quotas to boost the number of women ion the boardroom. She has described the current pace of change as "glacial".

Despite a flurry of female appointments in the wake of last year's government inquiry led by Lord Davies of Abersoch, which set a target of 25% female representation on FTSE boards by 2015, women still occupy fewer than one-in-five FTSE 100 boardroom seats, with new hires strongly biased towards part-time, non-executive roles rather than promoting full-time employees into the most senior jobs.

A report published earlier this week by the Chartered Management Institute also made grim reading. It found that female executives earn £400,000 less over the course of their working lives than male colleagues with identical careers – and are far more likely to be made redundant.

Ahrendts' comments came as Burberry reported almost a 30% drop in first-half profits to £112m on sales of £883m. The decline reflected the company's decision to start producing its own perfume and makeup.

In keeping with an industry-wide trend, the 156-year-old firm is buying back licences and has agreed to pay the French group Interparfums €181m (£145m) to sever its agreement, booking a £74m accounting charge. The fashion firm said the decision would not have an impact on profits in the short term, but Investec analyst Bethany Hocking predicted it would create a £71m boost by 2017.

The firm, best known for its raincoats lined with a distinctive camel, red and black check design, spooked investors with a profit warning in September that whipped £1bn off its stock market value. At that time it said growth had stalled in July and August, particularly in China, which has fuelled a near three-year boom in demand for luxury goods.

Burberry also revealed that the spending power of its more "aspirational" consumers – a term used to describe middle-class consumers who spend a large proportion of their disposable income on designer labels but cannot stretch to the most expensive items – had been hit by the faltering global economy.

It was able to make up some of the lost ground, with profit margins up in the six months to 30 September, as it sold a higher proportion of goods from its top-end lines to its wealthiest customers.

The growing divide between Burberry's wealthy shoppers and its middle-class customers has been reflected in the fortunes of its various brands. Its most expensive ranges, such as Prorsum, which it shows on the catwalk, and London, are doing well, while sales of the cheaper casualwear line, Brit, which includes jeans and polo shirts, have slumped.

Last month Burberry said sales had steadied in the final weeks of its second quarter and on Wednesday there was no change to its profit outlook for the second half. Shares closed down more than 4% at £11.99.